Optical sensing system for detecting welds and defects in metal

Abstract

An optical sensing system for detecting welds and defects in metal brightly illuminates a broad section of the metal and images a swath of the metal onto a multi-element detector array, generating voltage signals representing the reflectivity of the swath of the metal as it passes under the detector. A processor system detects areas of low reflectivity and indicates a defect. A slit mask placed in front of the detector array narrows the imaged swath to reduce false accepts. A color filter in front of the detector array reduces ambient light interference. The processor system incorporates an auto-calibration function to compare the current signal to an averaged reference signal.

What is claimed is:  
     
       1. A sensing system for detecting welds in a metal surface comprising: 
       a diffuse light source capable of illuminating a broad section of the metal surface;  
       a multiple element linear array of light detectors, the detector array generating a response proportional to the amount of light detected by each detector;  
       a lens for focussing light reflected from the metal surface toward the light detector array; and  
       a processor connected to the light detector array for observing and analyzing the detector array response;  
       wherein the processor further includes a weld determining element for determining a weld is passing under the sensing system when the processor observes an unusually low response from a detector.  
     
     
       2. The sensing system of  claim 1 , wherein the processor further includes a signal generating element for generating an indicating signal responsive to the weld determining element. 
     
     
       3. The sensing system of  claim 2 , wherein the processor further includes a display for displaying a message responsive to the indicating signal. 
     
     
       4. The sensing system of  claim 1 , further comprising a slit aperture mask placed between the lens and the detector array. 
     
     
       5. The sensing system of  claim 1 , further comprising a color filter placed between the lens and the detector array. 
     
     
       6. The sensing system of  claim 1 , wherein the processor further includes means for self calibrating. 
     
     
       7. A sensing and analyzing system for detecting welds and imperfections in a metal surface comprising: 
       a diffuse light source capable of illuminating a broad section of the metal surface;  
       a multiple element linear array of light detectors, the detector array generating a response proportional to the amount of light detected by each detector;  
       a slit aperture mask placed between the lens and the detector array;  
       a lens for focussing light reflected from the metal surface on the slit aperture mask; and  
       a processor connected to the detector array for observing and analyzing the detector array response and including means for determining when a weld is passing under the sensing system based upon the detector array response;  
       wherein the processor further includes means for generating a weld indicating signal responsive to the determining means.  
     
     
       8. The system of  claim 7 , wherein the determining means determines that a weld is passing under the sensing system based upon an unexpectedly low response from at least one detector in the detector array. 
     
     
       9. The sensing system of  claim 7 , further comprising a color filter placed between the lens and the detector array. 
     
     
       10. The sensing system of  claim 7 , wherein the processor further includes means for self calibrating.